The present invention relates to fiber optic networks, and more particularly to fiber optic connectors and functional blocks that enable fiber optic to the home while achieving a reliable and cost effective network.
Fiber To The Home (FTTH) is an attractive option that has received a significant amount of attention in recent years. Significant technological advances have been made in fiber optic communications. FTTH promises to deliver xe2x80x9ctruexe2x80x9d broadband access compared to existing access technologies including network connections based on phone lines (DSL) or coaxial cable. The hybrid-fiber-coax (HFC) architecture is a relatively recent development adopted by the cable industry in which optical signals are transported from a source of distribution (e.g., a headend) to multiple electro-optical conversion nodes via fiber optic cables. Each conversion node converts between optical signals and electrical signals using simple photo-detector technology, where the electrical signals are carried via coaxial cables routed from the conversion nodes to individual subscriber locations. Current HFC designs call for fiber nodes serving about 500 homes on the average, although the nodes could be further segmented to smaller coaxial-serving areas.
A xe2x80x9clast milexe2x80x9d solution to achieve FTTH would appear to be to replace the coax cables of an HFC architecture with fiber optic cables. The traditional approach to FTTH is to route a separate optical fiber to each subscriber location. Such a solution, however, results in about 1,000 fibers on the average between each local node and the neighborhoods served (2 per house for full duplex). The average number of fibers behind each person""s home in such a configuration is about 200. This has proved to be an unwieldy architecture that is difficult to establish and prohibitively expensive to maintain. FTTH has not yet proved to be cost effective to deploy and/or operate.
Experience from the coaxial cable configurations has demonstrated that cable problems can and do occur. Generally, damage to one or more cables reduces or otherwise eliminates service in corresponding downstream geographic areas. Coaxial cables are relatively inexpensive and easy to replace and/or repair. Fiber optic cables, on the other hand, are relatively expensive and difficult to repair. In proposed configurations, each cable has a multitude of optical fibers. During the installation process, the individual fibers must be identified and isolated to route each fiber to the appropriate location. Fiber optic cable repair has typically required very specialized equipment involving a sophisticated splicing operation that must be done in a relatively clean environment. The solution has been a truck loaded with very expensive fiber optic splicing equipment, referred to as a xe2x80x9csplicing vanxe2x80x9d. The general process is to clean, align and splice, which involves melting and firing the individual fibers. Although less of a problem for major thoroughfares, such as highways or rural access routes where van access is readily available, the splicing van must still be deployed to the trouble spot in the network. Even when access to the trouble spot is available, the splicing process can consume a considerable amount of time, sometimes several days. This is especially true in the last mile, where the cable is often routed in locations that are not van-accessible (such as someone""s back yard).
It is desired to solve the last mile dilemma so that FTTH become a viable and economic reality.
A fiber optic connector according to an embodiment of the present invention includes a body forming a fiber insertion path and an optical lens. The fiber insertion path is configured to receive an optical fiber and extends within the body to an internal end. The lens includes a first concave surface formed at the internal end of the fiber channel and a second concave surface formed on an external side of the body. The lens defines a centerline extending between the center points of the first and second concave surfaces. The first concave surface of the lens is operative to spread light sourced from an optical fiber inserted into the fiber channel towards the second concave surface and to re-direct light converging from the second concave surface towards the first concave surface onto the optical fiber. The second concave surface has a suitable size for visual inspection and cleaning. The second concave surface is configured to re-direct light diverging from the first concave surface to a direction generally parallel with the centerline and to re-direct light directed towards the second concave surface and in parallel with the centerline towards the first concave surface. The body may be configured to form a multiple optical fiber connector in which the body forms multiple individual fiber insertion paths and corresponding optical lenses.
The body may be made of a material that is optically transparent in an applicable wavelength range suitable for optical communications. The fiber insertion path may include a fiber guide chamber located between a fiber insert opening on an external side of the body and an opening of the fiber channel opposite the internal end. The fiber insert opening has a visible size suitable to facilitate threading an optical fiber. The fiber guide chamber is configured to guide an inserted optical fiber into the fiber channel. The fiber guide chamber is formed within the body and may have tapered walls between the fiber insert opening and the fiber guide channel opening. The fiber insert opening may have a size that is sufficient to encompass a fiber cable sheath inserted within.
The fiber optic connector may include a fiber tip cleaner located within the fiber insertion path that cleans a tip of an optical fiber while the optical fiber is inserted. The fiber tip cleaner may include, for example, at least one sheet of a low residue paper. The fiber optic connector may include a fiber bonding system located along the fiber insertion path that is operative to hold the optical fiber to the body after insertion. In a specific configuration, the fiber bonding system includes first and second epoxy chambers, first and second epoxy barriers, and first and second epoxy hammers. The epoxy chambers are provided within the body adjacent the fiber insertion path and filled with epoxy resin and hardener polymers, respectively. The epoxy barriers are positioned between the epoxy chambers and the fiber guide chamber operative to temporarily contain the epoxy polymers within the epoxy chambers. The epoxy hammers are provided in the body between outer opposing surfaces of the body and the epoxy chambers. The epoxy hammers are configured to force the epoxy polymers to breach the epoxy barriers to release the epoxy polymers into the fiber insertion path in response to compression applied to the first and second epoxy hammers.
In an alternative embodiment, an epoxy filter insert is provided that incorporates the fiber tip cleaner and the fiber bonding system. The epoxy filter insert may be configured to mount within the fiber insertion path. The epoxy filter insert may include, for example, a casing, a pair of epoxy chambers and at least one sheet of a low residue paper. The casing has an outer surface between a front end and a back end which is configured to mount to the inner walls of the body with the back end towards an opening of the fiber insertion path. The epoxy chambers are provided within and at the front end of the casing. The epoxy chambers are separated by suitable membranes and filled with epoxy polymers. The low residue paper sheet(s) are provided within and at the backend of the casing. The epoxy filter insert is positioned to block the fiber insertion path when mounted therein so that when an optical fiber is inserted, the tip of the optical fiber breaches the epoxy chambers allowing mixture of the epoxy polymers within fiber insertion path. The tip is also cleaned while breaching the low residue paper sheets while the optical fiber is inserted. The casing may have an outer surface that is conically-shaped to interface tapered walls of a fiber guide channel.
A complementary pair of fiber optic connectors according to an embodiment of the present invention are each configured with front ends that are configured to mate with the complementary connector to form a mated configuration. In the mated configuration, the second concave surfaces of the connectors are optically coupled to face each other in a concentric formation having a common centerline. The complementary pair may comprise male and female connectors or unisex connectors and may each incorporated multiple connectors.
An optical block according to an embodiment of the present invention includes a body, at least one optical functional unit provided within the body, a plurality of optical connectors mounted along an external surface of the body and a plurality of optical fibers. Each connector includes an optical lens. Each optical fiber is routed between an internal optical functional unit and a corresponding one of the optical connectors. Each lens of each connector includes first and second concave surfaces configured in a similar manner previously described.
The optical functional unit(s) may include a directional coupler and an n-way splitter. The directional coupler includes an input and first and second outputs and the n-way splitter includes an input and xe2x80x9cnxe2x80x9d outputs. In this embodiment, the unit includes an internal optical fiber connected between the second output of the directional coupler and the input of the n-way splitter. The optical connectors include an input connector, a tap output connector, and n splitter output connectors. The optical fibers include an input fiber optically coupled between the tap input connector and the input of the directional coupler, a tap output fiber optically coupled between the first output of the directional coupler and the tap output connector, and n splitter output fibers each coupled between an output of the splitter and a splitter output connector.
The optical functional unit may alternatively comprise an n-way combiner with n inputs and an output and a directional coupler having first and second inputs and an output. An internal optical fiber is coupled between the output of the combiner and the second input of the directional coupler. The optical connectors an input connector, an output connector and n combiner input connectors. The optical fibers include an output fiber optically coupled between the output connector and the output of the directional coupler, an input fiber optically coupled between the input connector and the first input of the directional coupler, and n combiner input fibers each optically coupled between an input of the combiner and a corresponding combiner input connector.
A segmented FTTH (Fiber to the Home) optical network that enables optical communication between a local optical communication node and multiple subscriber locations according to an embodiment of the present invention includes at least one segmented optical fiber, multiple optical taps and multiple subscriber optical fiber links. The segmented optical fiber is optically coupled to the optical communication node and routed near each subscriber location. The optical taps are distributed along the optical fiber dividing the optical fiber into a multiple segments. Each tap includes an input connector coupled to one optical fiber segment and an output connector coupled to an adjacent optical fiber segment. Each tap includes at least one splitter output connector. Each subscriber optical fiber link is coupled between a subscriber location and a corresponding splitter output connector of the optical taps.
The segmented FTTH optical network may include multiple optical combiners distributed along the optical fiber. Each combiner includes a segment input connector coupled to an optical fiber segment, a segment output connector coupled to an adjacent optical fiber segment, and at least one subscriber input coupled to a corresponding one of the subscriber optical fiber links. The segmented optical fiber, the optical taps, the subscriber optical fiber links and the optical combiners may be configured to support bi-directional optical communications. Alternatively, separate upstream and downstream segmented optical fibers may be included. In this latter embodiment, the optical fiber links each include a downstream subscriber link and an upstream subscriber link. The optical taps are distributed along the downstream segmented optical fiber, and the optical combiners are distributed along the upstream segmented optical fiber. Each combiner includes a segment input connector coupled to one optical fiber upstream segment, a segment output connector coupled to an adjacent optical fiber upstream segment, and at least one subscriber input coupled to a corresponding one of the upstream subscriber links.